Calculating partial distances from whole segment in grid using QGIS?

Question

I am using QGIS and trying to find a way to calculate partial distances of lines in a grid.

In the left part of the picture you can see the sum of the line lengths within the grid cell (108.96...), and the length of the whole yellow line/segment that intersect it in black (146.37...).

How do I trim the yellow line to multi-lines which will show the proportional length in each cell (i.e 108.96+...+Len(Xn) =146.37)?

Answer 1

I figured it out myself - It is 2 steps process: 1. intersect the lines with the grid layer so all lines are split into segments. 2. Using field calculator: $length of the line layer